On 05/08/2013 11:36 PM, RAHUL RAJ wrote:
Checkout the following code:
sample2 = [x+y for x in range(1,10) for y in range(1,10) if x!=y]
output=[]
output=[x for x in sample2 if x not in output]
This statement is not doing what you expect. It is not building a list
in the variable named output, it is building a list (anonymously) then
binding it to the variable output once it's built. Therefore output is
[] for the whole list building operation.
The later operation works, because your *are* building the list in place
as you go.
the output I get is
3 4 5 6 7 8 9 10 3 5 6 7 8 9 10 11 4 5 7 8 9 10 11 12 5 6 7 9 10 11 12 13 6 7 8
9 11 12 13 14 7 8 9 10 11 13 14 15 8 9 10 11 12 13 15 16 9 10 11 12 13 14 15 17
10 11 12 13 14 15 16 17
which contains duplicate values.
But if I do like this:
sample2 = [x+y for x in range(1,10) for y in range(1,10) if x!=y]
output=[]
for x in sample2:
if x not in output:
output.append(x)
the value of 'output' I get like this:
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
I know that both the programs have the same functionality, but why do I have
different outputs?
Please help!
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